Find Qt5 or Qt6 based on the QT_VERSION variable passed

Author: diffstorm

CMakeLists.txt

@@ -11,17 +11,16 @@ set(CMAKE_CXX_STANDARD 11)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
 # Find Qt
-find_package(Qt6 COMPONENTS Core Gui Network SerialPort Widgets REQUIRED)
-find_package(Qt5 COMPONENTS Core Gui Network SerialPort Widgets)
-
-if(Qt6_FOUND)
-    set(QT_VERSION 6)
-    message(STATUS "Using Qt 6")
+if(QT_VERSION EQUAL 6)
+    find_package(Qt6 COMPONENTS Core Gui Network SerialPort Widgets)
     set(QT_LIBS Qt6::Core Qt6::Gui Qt6::Network Qt6::SerialPort Qt6::Widgets)
-else()
-    set(QT_VERSION 5)
-    message(STATUS "Using Qt 5")
+    message(STATUS "Using Qt 6")
+elseif(QT_VERSION EQUAL 5)
+    find_package(Qt5 COMPONENTS Core Gui Network SerialPort Widgets)
     set(QT_LIBS Qt5::Core Qt5::Gui Qt5::Network Qt5::SerialPort Qt5::Widgets)
+    message(STATUS "Using Qt 5")
+else()
+    message(FATAL_ERROR "QT_VERSION not specified or invalid. Use -DQT_VERSION=5 or -DQT_VERSION=6")
 endif()
 
 # Add source files